This invention relates to camlocks, and more particularly to spring-loaded camlocks or latch assemblies and other rotatable latch closure mechanisms.
Rotation camlocks or latches are well known in the art. Typically, such a rotation latch has a housing that can be mounted to a door and containing a central bore. A plug is rotatably mounted in the bore of the latch housing and capable of rotating a cam or pawl between a locked and unlocked position. Rotation of the plug between the locked and unlocked positions is accomplished by an operator either by turning a handle on the top side of the plug or by inserting a properly shaped tool into the top side of the plug and turning the tool.
The camlocks on the market, however, require the operator to rotate the plug into the locked position as well as out of the locked position and into the unlocked position. This is inconvenient in most applications and is not adequate in certain applications, especially where a rotation requires a separate tool inserted into the top side of the plug.
Therefore, when closing a door having a standard camlock, the plug must be initially in the unlocked position and then manually rotated from the unlocked position to the locked position once the cam has cleared the strike plate or other structure designed to cause closure with the cam. This is a somewhat inconvenient operation even for a camlock equipped with a handle.
Many applications, however, require or benefit from a camlock that does not have a handle. A camlock may be designed to have a very low profile or even designed to be flush with the surrounding door surface. Such a low profile or flush camlock normally comes with a plug that has a particularly shaped depression on its otherwise flush surface. The depression is shaped to match a turning tool. As a result, the flush camlock is fully operational only with a turning tool. This makes the above-described steps for closing and locking the door particularly inconvenient. Additionally, where a door must be returned to the closed and locked position at all times, such as for safety or security reasons, this procedure of having to reach for the turning tool to close and lock the door is in fact inadequate.
What is needed is a camlock that is biased to the locked position such that a door having such a camlock may be closed and locked in a single motion without having to manually rotate the plug. The problem, however, is that typical camlocks leave no room for a biasing spring, especially in applications that prefer and utilize a low profile camlock.
Typically, the diameter of the bore in the housing and the diameter of the plug are sized to result in little, if any, play. The bore surface is typically coated with a grease to provide a slick surface within which the plug smoothly rotates. Thus, there is no room for a biasing mechanism in the typical camlock.
This invention involves a rotation camlock assembly having a spring, a first body rotatably mounted within a second body, and a cam or pawl mounted to said first body. The first body is a plug or actuator that rotates with respect to the second body, the rotation being regulated by a spring mechanism in combination with a rotation limiting member. The rotation limiting member limits rotation to a 90xc2x0 turn in the one embodiment; however, other ranges of motion are contemplated by this invention. The second body or latch housing is mounted to either a door or a stop structure associated with a door for the closure and latching of said door. The cam or pawl member rotates between a first position in which the latch assembly is disengaged and a second position in which the latch assembly is engaged, locking the door to the stop structure.
The top surface of the plug is equipped with either a handle or specifically shaped depression so that the plug may be rotated between the latched and unlatched positions. The spring is assembled in the camlock with a pre-set tension causing the plug and cam to be biased to the locked position. The amount of tension in the spring is sufficient to cause the plug and cam to return to the locked position at all times when a force is not applied to them, but not too strong, however, such that it would prevent rotation of the plug and cam by either a force applied to the top side of the plug or by an appropriate force applied to the cam.
As a result, in operation a locked door having a camlock of the present invention may be unlocked by turning the handle or by inserting and turning a tool having the necessary shaped end piece to fit the depression on the top surface of the plug. When the operator""s hand or the tool is removed from the handle or plug, the spring we cause the plug to return to the locked position. In order to close and lock the door, however, all that is needed is to handle or plug, the spring we cause the plug to return to the locked position. In order to close and lock the door, however, the operator need only push the door shut. The cam and strike plate are shaped and positioned such that when the cam comes in contact with the strike plate, the force exerted on the cam causes the cam to rotate from the locked position enough for the cam to clear the strike plate. Once the cam has cleared the strike plate, the spring forces the cam to rotate back to the locked position. The camlock thereby locks the door closed as the result of the single motion of pushing the door closed. The camlock remains locked closed until an operator manually rotates the plug and opens the door as described above.
The entire latch assembly is small enough to fit in a standard half-inch bore in the door. The outer surface of the latch housing has two or more flattened sides to match the flattened surfaces of the bore so that the latch housing does not rotate relative to the door. The top surface of the latch housing and plug have a very low profile, nearly flush with the top surface of the door. Thus, the entire latch mechanism is housed substantially in the bore in the door, although the cam extends beyond the bottom surface of the door and, depending on the width of the door and the positioning of the strike plate, the latch may also extend somewhat beyond the bottom surface of the door.
An object of the present invention is to provide a rotation latch or camlock that is flush or near flush with the surface of the surrounding door.
Another object of the present invention is to provide a latch assembly that causes the cam of the camlock to be biased in the locked position such that manual operation of the latch is necessary only in the unlocking direction.
A further object is to provide a camlock that requires no manual turning of a handle or other turning device in order to close and lock a door.